Process of tanning



Patented Mar. 22, 1938 2,111,800

u rs srAss PAT PROCESS OF. TANNING Theodore F. Oberlander, Elkland, Pa.

No Drawing. Application June 2'7, 1934, Serial No. 732,624

4 Claims. (01. 149-5) This invention relates to the treatment of hides leather Without destroying the beneficial effect and leather. It isan object of this invention to of the other ingredients. produce a leather with an improved quality and Another typical method is to use a desired durability. It is a further object to provide a amount of magnesium carbonate in the oil wheel 5 process which will control the acid content of during the process of adding oil, sugar or Epsom the leather and thereby increase its length of salts to the leather. life and serviceability. It is a further object to In any case the amount of magnesium carproduce a leather which will be of a uniform bonate to be added to the solutions will depend quality with a minimum of expense and difficulty. on the solution used and the character of the It is a further object to devise a process for the leather to be treated and produced, and the most 10 production of leather which will be simple to opdesirable proportion can most readily be detererate and which will be effective and reliable in mined by the results. its results. 7 Leather made in accordance with this process In the treatment of leather the raw hide, after may be kept with a substantially uniform conthe hair and flesh are removed, is treated with a tent, for example, between 0.3% and 0.7% of 5 tanning solution to convert the hide into leather. acidity. It may then be washed and bleached either by the The use of other carbonates than magnesium use of soda ash or other bleaching agent, therecarbonate is not so effective, some of such after it may be tumbled in a. drum with a filler carbonates for example as sodium carbonate solution, molasses, Epsom salts or the like. The when used in appreciable quantity tends. to pre- 20 leather may then, if desired, be again soaked vent the functioning of the tanning process and in a cellulose sulphate or tanning material and other carbonates such as barium carbonate are again treated with fillers, sugar, Epsom salts and. too inert to be of value. oil. For many purposes this second step may Since certain changes may be made in the be omitted. After the leather is treated it may above construction and difierent embodiments of' be conditioned so that it may be compressed by the invention could be made without departing a. press or rolling machine and it may be further from the scope thereof, it is intended that all bleached if desired by dip-ping in a sponge or dipmatter contained in the above description shall FFHQE ping compound. be interpreted as illustrative and not in a limit- The finished leather produced by the above ing sense. 30 process has a serious drawback in that it is apt It is also to be understood that the following to have an unduly high acid content which makes claims are intended to cover all of the, generic it unsuitable for many purposes and which is deand specific features of the invention herein de-' structive of its durability. This acidity may be scribed, and all statements of the scope of the in due to the acids of the tanning solution or it vention which, as a matter of language, might 35 may be due to the acids used in bleaching and be said to fall between said claims. it may run as high as two percent of free mineral Having described my invention, what I claim acid. I as new and desire to secure by Letters Patent In accordance with this invention it has been is:

40 found that the effect of these acids insofar as 1. The process of tanning which comprises 40 they produce an acidity in the finished leather treating the hides with a vegetable tanning solumay be substantially neutralized by the use of tion and subsequently neutralizing the acidity magnesium carbonate in solution either in. the with magnesium carbonate. presence of the tanning materials or after the 2. The process of tanning which comprises last acid bath without in any manner destroytreating the hides with magnesium carbonate in 45 ing or counteracting the essential purposes of the conjunction with vegetable acid materials to contanning acids in the formation of the leather. trol the acidity of the finished hide.

A typical method oi'using it will be to make up 3. The process of treating leather which cona mixture of the following approximate proporsists in subjecting vegetable tanned hides to the tions, 50% powdered tanning or filling extract, action of magnesium carbonate in solution. to 50 l 8% oxalic acid, 1% borax, 10% Glauber salts, limit the final acidity. 8% magnesium carbonate, 5% kaolin, 1% sodium 4. 'Ihe process of treating leather which conacid sulphate or potassium acid sulphate and sists in subjecting it to a vegetable acid tanning 17% sodium chloride. solution in the presence of magnesium carbonate. 5 When used in this manner the magnesium carbonate serves to control the acidity in the finished I T. F. OBERLANDER. 

